This invention relates to the field of envelopes and more particularly to envelopes having a window through which the contents of the envelope can be viewed and most particularly to envelopes for the retail display and sale of garden and landscaping seed.
Seeds packaged for the home or retail market have long been displayed by retailers in racks having an array of envelopes containing available seeds for a variety of plants. Initially, such seed packs were made entirely of paper and eventually colored pictures of the associated plants were printed on the front of the paper envelopes so the consumer could see the plant that would develop from the seeds contained in the seed pack. A later development was the use of a window in the front panel of the seed envelope to allow a customer to view some of the contained seed. Windows are commonly formed in envelopes by forming an aperture in the sheet of paper or other envelope material and then bonding a sheet of transparent window material across the aperture. The transparent window material extends beyond the boundaries of the aperture so it overlaps onto the paper and is bonded to the paper sheet along at least a portion of the overlap. This forms a window through the aperture.
Paper remains a desirable sheet material for forming the principal part of a seed envelope because paper is strong and durable, inexpensive and provides a surface that readily accepts the printing of quality pictures. A crease formed at a fold in paper is also relatively stiff or rigid thereby helping to maintain the envelope in a straight, non-sagging upright position. Windows too remain a desirable feature of seed envelopes. However, seed envelopes and envelopes generally have been limited to windows that are relatively small. Most prior art envelope windows extend over only a portion of one of the panels forming the envelope, usually the front panel. Such a window is suitable for most envelope uses because most envelopes are made to contain folded paper sheets or other flat objects and the windows are not intended to reveal the entire contents of the envelope. Most envelope windows are intended to reveal an address, a symbol or brief message or merely that there is something in the envelope. There have also been envelopes with narrow windows that extend around an edge of an envelope.
It would be desirable for a seed envelope to have a window that allows viewing of the entire seed contents of the envelope. Such improved visibility would permit a consumer to view all the seed in order to see the quantity of seed in the envelope and to verify its quality. It would be particularly desirable to have a window that even allowed viewing from the side and back of the envelope because that would give prospective purchasers an even better perspective on the quantity and quality of the seeds.
One difficulty that is encountered in designing a windowed seed envelope arises because seeds are particles that behave like a fluid because they flow somewhat like a liquid. As a result of this fluid characteristic, a quantity of seed filled into an envelope tends to apply distributed forces against the front, back, sides and bottom of the envelope. These forces cause the front and back panels of the envelope to spread, separate and move apart like the walls of a sack. The distance of separation is typically ⅛″ to ½″ depending on seed size and weight. As a result, the fold creases and especially the corners of the envelope are stressed by the seed contents considerably more than the minimal stress caused by insertion of a flat object into an envelope. Because of these stresses, it is common for seed envelopes to tear and for seeds to leak from a seed envelope. The inclusion of a relatively large window in a seed envelope, especially a window that extends to the edges of the envelope, creates additional opportunities for weak areas that would be subject to being torn by the stress applied by the contained seed. Because it is desirable to have a seed envelope that is a composite that is formed principally of paper but has a transparent window material that is a plastic material, and because the formation of a window aperture in the paper reduces the strength of the envelope in some areas of the envelope, the size of windows in seed envelopes has been limited.
Therefore, it is an object and feature of the invention to provide a seed envelope that has a greatly enlarged window and yet has the strength to retain its seed contents.
Another object and feature of the invention is to provide a seed envelope with a window that extends beyond both the side edges onto the back of the envelope and to the bottom edge of the envelope and preferably beyond the bottom edge onto the back of the envelope and yet have the strength to retain seed particulates despite the wrap around windows. This feature allows not only viewing of the seed contents from the front and rear of the envelope but also allows viewing of the seed contents from the side as a result of the spreading of the front panel from the back panel of the envelope in response to the fluid forces applied by the seed contents.